"never attribute to malice that which is adequately explained by stupidity..." -Hanlon's razor
Best use of it is in your personal life with family, friends, retail worker in your local grocery shop etc.
(I don't think it applies here though)
Actually, that frequently is malice, but it's malice on the part of the grocery shop, not the individual worker.
Proposed addendum: never attribute to personal malice what can be adequately explained by institutional malice.